Question

This post is the continuation of my previous post. Now I have a code that I’d like to compile. The only difference is that now I’m using lists of my own class List<Row> instead of List<Integer[]>. In particular look at hashCode in Row, because it provides a compilation error.

    public class Row {
          private String key;
          private Integer[] values;

          public Row(String k,Integer[] v) {
              this.key = k;
              this.values = v;
          }

          public String getKey() {
              return this.key;
          }

          public Integer[] getValues() {
              return this.values;
          }

          @Override
          public boolean equals(Object obj) {
              if(this == obj)
                  return true;
              if((obj == null) || (obj.getClass() != this.getClass()))
                  return false;
              // object must be Row at this point
              Row row = (Row)obj;
                  return ((key == row.key) && (values == row.values));
          }

          @Override
          public int hashCode () { // HERE I HAVE A PROBLEM. DON'T KNOW HOW TO IMPLEMENT IT
              return this.key;
          }

    }

public class Test {

    public static void main(String[] args) {
        List<Row> allRows = new ArrayList<Row>();
        allRows.add(new Row("0",new Integer[]{1,2,3}));
        allRows.add(new Row("0",new Integer[]{1,2,2}));
        allRows.add(new Row("1",new Integer[]{1,2,3}));
        allRows.add(new Row("2",new Integer[]{1,1,1}));
        allRows.add(new Row("2",new Integer[]{1,1,1}));

List<Row> selectedRows = new ArrayList<Row>();
            selectedRows.add(new Row("0",new Integer[]{1,2,3}));
            selectedRows.add(new Row("2",new Integer[]{1,1,1}));

    System.out.println(allRows);
    System.out.println(selectedRows);
        List<Row> refreshedRows = refreshRows(allRows,selectedRows);
        System.out.println(refreshedRows);

    }

    private static List<Row> refreshRows(List<Row> allRows,List<Row> selectedRows) {
        Set<Row> set1 = new HashSet<Row>();
        Iterator<Row> it = allRows.iterator(); 

        while(it.hasNext()) {
            Row curr = it.next();
            if (!set1.add(curr) && selectedRows.contains(curr)) {
                it.remove();
            }
        }
        return allRows;
    }
}

The result, i.e. refreshedArray, should be equal to:

key = "0", values = {1,2,3}
key = "0", values = {1,2,2};
key = "1", values = {1,2,3};
key = "2", values = {1,1,1};

Answer 1

Try with the following. Despite minor changes, most of the code is generated by Netbeans IDE 7.0:

@Override
public boolean equals(Object obj) {
    if (this == obj) {
        return true;
    }
    if (obj == null) {
        return false;
    }
    if (getClass() != obj.getClass()) {
        return false;
    }
    final Row other = (Row) obj;
    if ((this.key == null) ? (other.key != null) : !this.key.equals(other.key)) {
        return false;
    }
    if (!java.util.Arrays.deepEquals(this.values, other.values)) {
        return false;
    }
    return true;
}

@Override
public int hashCode() {
    int hash = 3;
    hash = 79 * hash + (this.key != null ? this.key.hashCode() : 0);
    hash = 79 * hash + java.util.Arrays.deepHashCode(this.values);
    return hash;
}